*** Example analysis input files for CZM analysis of delamination growth in a DCB specimens ***

Authors:
J.A. Pascoe; Imperial College London / current: Delft University of Technology; j.a.pascoe@tudelft.nl; https://orcid.org/0000-0003-2771-8285
S. Pimenta; Imperial College London; soraia.pimenta@imperial.ac.uk; https://orcid.org/0000-0002-1603-5940
S.T. Pinho; Imperial College London; silvestre.pinho@imperial.ac.uk; https://orcid.org/0000-0001-5727-7041

** Introduction **
The files in this collection accompany the paper 'How to set up a cohesive zone model for an LEFM dominated problem: a detailed analysis for first time users', submitted to Applied Mechanics Reviews. The files comprise input files that allow reproduction of the example analyses shown in that paper. The purpose of the paper is to show how to determine appropriate values of various numerical parameters required when setting up a cohesive zone model analysis of an LEFM dominated crack propagation problem. These parameters can be determined by running a series of convergence studies. The input files for those convergence studies as well as the final prediction are included in this collection.

The example analyses for the paper were run using Abaqus/Standard 6.14, and the included files will work for that software version. Many other FE codes, both commerical and open source, offer CZM capability. The use of Abaqus in this case was based on availability of the software, not on a comparative analysis of different codes.  We provide these input files as an extra addition for readers of the paper who also have access to Abaqus. This should not be interpreted as an endorsement of Abaqus over alternative FE codes by the authors.

** Model description **

The model represents a 2D analysis of a double cantilever beam (DCB) specimen consisting of two unidirectional carbon fibre reinforced polymer arms. The specimen has a length of 130 mm, an initial crack of 57.5 mm and a total thickness (both arms) of 3.52 mm. The arms are meshed using 4 node plane strain elements (CPE4R) and a line of single cohesive elements (COH2D4) was placed along the interface between the two arms. The bottom left node was pinned, and a displacement was prescribed on the upper left node.

** Dataset structure **
The input files in this dataset are grouped into 4 folders, corresponding to the four different convergence studies described in the paper. The file 'FinalPrediction.inp' is the input file for the final prediction of the force-displacment and crack-length vs displacement curves.

** Baseline values **
During the convergence study the parameter being studied was varied, while the other parameters were kept at the constant baseline value. These baseline values were:

Cohesive stiffness:  10^6  MPa/mm
Cohesive strength:   50    MPa
Mesh size:           0.1   mm
Viscosity parameter: 10^-6 s

** Material properties **
The material properties used in this example are representative for a typical aerospace grade carbon fibre / epoxy composite laminate, with a unidirectional lay-up (all fibres aligned with the length direction of the specimen).

The material properties were:

E11: 	160 GPa
E22:	9.0 GPa
G12:	5.0 GPa
nu12:	0.32
GIc:	0.2 kJ/m^2